Commercial and Cost Effective Production of Gas Electron Multiplier (GEM) Foils

Particle tracking detectors are used extensively in nuclear and high energy experiments supported by the DOE. New advances in the technology of micropattern detectors, and in particular Gas Electron Multipliers (GEMs), offer significant improvements in performance over traditional tracking detectors. This project will develop a commercial source of GEM foils for use in the nuclear and high energy research community. Phase I involved a systematic investigation of various aspects of the production of GEM foils. Detailed measurements were made on the physical properties of the foils, such as hole size, hole spacing, and hole geometry. The principle cause of a gain instability was identified and solved by the use of a cleaning agent in the last stage of production. Overall, the study has lead to a much better understanding of the manufacturing process and to improved performance of the foils. Phase II will concentrate on improving the quality, reliability, uniformity and gain stability of the GEMs. Specific studies will involve measurements of gain stability over time, spatial gain uniformity, and rate dependent effects. The primary objectives of Phase II will be to identify the critical manufacturing parameters involved in producing reliable high-quality foils and to develop a capability for producing larger foils, while maintaining good quality control. Commercial Applications and other Benefits as described by the awardee: GEM detectors have potential use in many types of research, such as nuclear physics, high energy physics and astrophysics, as well as in medical imaging, nuclear non-proliferation, and homeland security applications.